This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Structural DNA nanotechnology uses unusual DNA motifs to build target shapes and periodic arrangements. We expect these systems can be applied to several practical ends: The key motivating goal for this research is that spatially periodic networks are crystals. Also the Steepest challenge of the research is the construction of 3D crystals with high order. If we can build stick-figure crystalline cages in the nanometer scale, they could be used to orient other biological macromolecules as guests inside those cages, thereby rendering their 3D structure amenable to diffraction analysis. The globular shapes of proteins are not conducive to the packing alignment that is essential to form a well-ordered crystal, due to specific interactions between DNA and proteins, DNA 3D crystalline crystal is an excellent candidate for forming periodic crystalline cages that can host proteins in order for the X-ray diffraction studies;Similarly, the same crystalline arrays could be used to position and orient components of molecular electronic devices with nanometer-scale precision. A number of designs using unusual DNA motifs have been self-assembled to yield 3D crystals. Although we have been successfully build 2D arrays, the structural criteria of success with 2D arrangements are based typically on AFM observation with resolution limit of 3-10 nm. By contrast the goal for successful work of x-ray diffraction is around 2 [unreadable][unreadable][unreadable] . However the diffraction patterns of our preliminary crystals have been limited to 10 [unreadable][unreadable][unreadable] . Six-DNA helix-Bundle is the exact motif I[unreadable][unreadable][unreadable][unreadable][unreadable]"m using for this research. In this motif six DNA helices associate to form a hexagon arrangement if you look down the helical axis of DNA. We use thermo-control and vapour-diffusion methods. We have been successfully made 2D arrays by using the former method.